1. Field of the Invention
The present invention relates to a transmission device, an imaging device, a transmission system, a receiving device, and a transmission method. For example, the present invention relates to a technique in which a signal is transmitted between devices by using a triax cable.
2. Description of the Related Art
In the related art, in a broadcasting station a plurality of cameras are connected to a camera control unit (referred to as CCU hereinafter) by using a cable. Then, along the cable, video signals and audio signals, which are captured by the cameras, are transmitted to the CCU. In addition, return signals used for instructions and confirmation are transmitted to the cameras from the CCU.
Usually, a triax system is adopted as a signal transmission system. According to a triax system, power, a video signal, an audio signal, a command signal, and a camera return signal can be transmitted along one cable. Usually, these signals are modulated into FM waves or AM waves and transmitted by using a frequency-division multiplex system. In addition, since the cost of a coaxial cable is relatively low, generally a coaxial cable is used as the cable used for connecting the cameras and the CCU.
On the other hand, in recent years, signals which comply with the High Definition Television (HDTV) system have become prevalent, the HDTV system being capable of transmitting a larger amount of image information than the existing National Television Standards Committee (NTSC) system or the like. Namely, it is necessary for the triax system to optimally transmit these signals.
However, according to the analog transmission system mentioned above, there is a problem in that it is difficult to maintain the transmission quality of these signals. Therefore, for example according to Japanese Unexamined Patent Application Publication No. 10-341357, a signal to be transmitted is converted into a digital signal and transmitted by using a triax system.